Underwater cable cutter

ABSTRACT

AN UNDERWATER CABLE CUTTER INCLUDING: A PISTON AND A CYLINDER, THE CYLINDER BEING CLOSED AT A TOP END, THE PISTON HAVING A ROD WHIHC SLIDABLY EXTENDS THROUGH THE BOTTOM END OF THE CYLINDER, THE BOTTOM END OF THE ROD HAVING A CUTTING EDGE WHICH IS CAPABLE OF CUTTING A CABLE, MEANS MOUNTED ON THE CYLINDER FOR RETAINING A CABLE FOR CUTTING BY SAID CUTTING EDGE, AND AN APERTURE IN THE CYLINDER FOR INTRODUCING SEA PRESSURE FOR ACTUATING SAID PISTON.

Sept. 21, 1971 c, RIQRDAN 3,605,812

I I UNDERWATER CABLE CUTTER Filed Feb. 16. 1970 2 Sheets-Shoot 1 mvsmon. 62 RAYMON c. RIORDAN ERVIN F. JOHNSTON ATTORNEY.

United States Patent 3,606,812 UNDERWATER CABLE CUTTER Raymon C. Riordan, Arcadia, Calif., assignor to the United States of America as represented by the Secretary of the Navy Filed Feb. 16, 1970, Ser. No. 11,525 Int. Cl. B26d /12 US. Cl. 83-453 11 Claims ABSTRACT OF THE DISCLOSURE An underwater cable cutter including: a piston and a cylinder, the cylinder being closed at a top end; the piston having a rod which slidably extends through the bottom end of the cylinder; the bottom end of the rod having a cutting edge which is capable of cutting a cable; means mounted on the cylinder for retaining a cable for cutting by said cutting edge; and an aperture in the cylinder for introducing sea pressure for actuating said piston.

STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION In oceanographic exploration it is frequently necessary to submerge instruments such as hydrophones, transducers, or other sensing devices, to depths of several thousands of feet below the surface. This is commonly accomplished by fastening a float to a bottom anchor by means of a support cable and suspending the oceanographic instrument on the cable at a predetermined depth or fixed distance from the bottom. A preferred method of retrieving the oceanographic instrument is to break the connection between thet cable and the anchor so as to allow the float to ascent the instrument to the surface of the water. When this method is employed the anchor is a type which is expendable.

Several devices already exist for releasing the float and instrumentation from the expendable anchor. Most of these devices are located along the cable between the anchor and the instrumentation and are actuated by a timed release means or by an acoustic command from a surface vessel. The timed release approach has the serious limitation of releasing the instrumentation at a future time which may not be favorable from the standpoint of weather and other recovery conditions. The acoustic command release approach has resulted in an undesirably large and expensive mechanism as well as having the problem of accidental actuation by stray noises.

SUMMARY OF THE INVENTION The present invention overcomes the disadvantages associated with the prior art release devices by providing an underwater cable cutter which utilizes hydrostatic pressure to cut the cable between the expendable anchor and the instrumentation to be recovered. The present cable cutter is inexpensive to construct and yet performs in a highly eflicient manner. The cutter can be remotely actuated at a time which is favorable for recovery and there is no danger that stray acoustic electromagnetic signals will prematurely actuate the device. These unusual combination of advantages have been accomplished by providing a piston and cylinder wherein the cylinder is closed at a top end, the piston having a rod which slidably extends through the bottom end of the cylinder; the

3,606,812 Patented Sept. 21, 1971 ice STATEMENT OF THE OBJECTS OF THE INVENTION \An object of the present invention is to overcome the aforementioned problems associated with the prior art underwater release devices.

Another object is to provide an underwater cable cutter which is inexpensive to make and highly efficient in operation.

A further object is to provide an underwater cable cutter which can be actuated at a time which is favorable for recovery and yet is immune from stray acoustic and electromagnetic signals.

Yet another object of the present invention is to provide an underwater cable cutter which can be actuated by a trained porpoise.

Other objects and many of the attendant advantages of this invention will be readily appreciated as it becomes better understood by reference to the description and accompanying drawings which follow.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an undrwater elevational view illustrating an oceanographic instrument suspended by a float above an expendable anchor, and the underwater cable cutter located therebetween.

FIG. 2 is an exploded isometric view of the underwater cable cutter.

FIG. 3 is a longitudinal cross sectional view of the cable cutter.

FIG. 4 is a longitudinal cross sectional view of a plug which may be used in combinataion with the cable cutter.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings wherein like reference numerals designate like or similar parts throughout the several views, there is shown in FIG. 1 an oceanographic instrument 10 which is connected to an expendable anchor 12 by a cable 14, and which is suspended at a predetermined depth in the water by a float 16. Located within the cable 14, and between the oceanographic instrument 10 and the expendable anchor 12 is an underwater cable cutter 18. The cutter 18 has the capability of cutting the cable 14 at the bottom end of the cutter so that the float 16 will float the oceanographic instrument 10 to the surface of the water at a desired time for recovery.

As shown in FIGS. 2 and 3 the underwater cable cutter 18 includes a piston 20 and a cylinder 22, which may be closed at its top end by a threaded cap 24. A lift ring 25 may be welded to the top of the cap 24. The piston 20 has a rod 26 which slidably extends through a passageway 28 in the bottom end of the cylinder 22- The piston rod 26 may be mounted to the piston 20 by any suitable means such as a flange 28 and bolts 30. In order to seal the interior of the cylinder 22 from the outside pressure environment a gasket 32 may be provided between the cap 24 and the remainder of the cylinder, and an O-ring 34 may be provided in the cylinder passageway 27. The cylinder passageway 27 may be appropriately grooved for receiving the O-ring.

The cable 14 is connected at the bottom end of the cylinder 22. In order to cut this cable and release the oceanographic instrumentation the bottom end of the piston rod 26 is provided with a cutting edge 38. This cutting edge may be formed by a semi-circular projection of the piston rod which has a cutting face 40 which is substantially coextensive with the longitudinal axis of the piston rod. The cutting edge 38 is forced at a selected time in a downward direction by hydrostatic pressure. The hydrostatic pressure is introduced into the cylinder 22 by an opening in the cylinder such as an aperture 42 which may be located in the cylinder cap 24.

Mounted on the bottom end of the cylinder 22 is a means for retaining the cable for cutting by the cutting edge 38 of the piston rod. As shown in FIG. 1 the preferred embodiment of the invention receives a loop 44 of the cable from the expandable anchor 12. It is this loop that is cut and enables recovery of the oceanographic instrument 10. In this preferred embodiment the cable retainer means has a passageway (to be described in detail hereinafter) which is capable of leading the cable within the loop 44 at an angle to the longitudinal axis of the piston rod. The cable retainer means may include a block which is divided into two portions 46 and 48. The block portion 46 may be rigidly fixed to the bottom end of the cylinder 22 and the other block portion '48 may be removable from the fixed block portion 46. Each block portion 46 and 48 has a respective cutting face 50 and 52 which are substantially coextensive with the longitudinal axis of the piston rod and the cutting face 40 of the piston rod. With such an arrangement the cutting edge 38 of the piston rod may slide across the cutting faces 50 and 52 to cut the loop 44 of the cable.

In order to properly position the loop 44 of the cable for cutting by the cutting edge 38 of the piston rod the fixed and removable block portions 46 and 48 may each be provided with a respective projection 54 and 56 which when combined form a passageway 58 for the cable. The projection 54 has a planar face 60 which is perpendicular to the fixed block portion 46, and the projection 56 has an arcuate face 62 which is curved 90 and which is perpendicular to the removable block portion 48. When the block portions 46 and 48 are fitted together the passageway 58 curves 90 from a direction parallel to the longitudinal axis of the piston rod 26 to a direction which is perpendicular to the axis. It should be noted that this novel arrangement enables the block portions 46 and 48 to receive the loop 44 of the cable and place the loop in a cutting position with respect to the cutting edge 38 of the piston rod 26 without undue strain on the loop. Further, the planer face 60 of the projection 54 enables the loop 44 to be easily captured in the passageway 58 when a user assembles the two block portions 46 and 48.

In order to facilitate assembly of the block portions 46 and 48 the fixed block portion 46 may be provided with a pair of alignment holes 64, and the projection 56 of the removable block portion may be provided with a pair of alignment pins 66. Upon registering the pins 66 with the alignment holes 64 the block portions 46 and 48 are properly assembled so as to form the passageway 58. The block portions 46 and 48 may be fastened together by any suitable means such as bolts 68.

In order to close the aperture 42 from the outside water environment a plug 70 may be employed. As shown in FIG. 4, the plug may be constructed of a resilient material, such as neoprene, and bonded within the plug along its longitudinal axis there may be two twisted ends of a wire loop 72. The loop 72 may be manually pulled for withdrawing the plug 70 from the aperture '42. This may be accomplished by a diver, or if the depth is too great by a line (not shown) which is connected to the loop 72 and extends to the surface by a float (not shown). In the preferred embodiment the loop 72 is of a size which is suflicient to form a neck ring for a porpoise. With such an arrangement a trained porpoise may be utilized for capturing the loop 72 and pulling the plug 70 from the aperture 42. It should be understood that a soluble plug could be utilized in lieu of the resilient plug 70. Salt or sugar have been utilized as soluble plugs and such materials may fill the aperture 42 and dissolve after a predetermined time to actuate the cable cutter 18.

In the operation of the present device the oceanographic instrument 10 is connected at a bottom end to the expendable anchor 12, and at a top end to a float 16. The cable cutter 18 is interconnected in the cable 14 between the expendable anchor 12 and the oceanographic instrument 10. The lower portion of the cable 14 has a loop 44 which extends through the cable retainer means at the bottom end of the cutter 18 and the upper portion of the cable 14 is looped around a lift ring at the top end of the cutter. This whole assembly may be simply thrown over the side of a surface vessel and it will go into the position which is illustrated in FIG. 1. When recovery conditions are favorable the surface vessel may release a porpoise which is trained to capture the loop 72 and pull the plug 70 from the aperture 42. Since the cable cutter originated at atmospheric pressure hydrostatic pressure will enter through the aperture 42 and force the piston 20 in a downward direction. This will cause the cutting edge 38 of the piston rod 26 to slide across the cutting faces 50 and 52 of the block portions 46 and. 48 to sever the cable loop 44. When the cable loop 44 is severed the float 16 will ascend the oceanographic instrument 10 and the cable cutter 18 to the surface of the water where this assembly may be retrieved by the surface vessel.

It should be noted that in the preferred embodiment the cable cutter 18 is arranged to cut a cable which is configured in a loop. In certain instances it may be desirable to cut a cable in its straight form. If this is desired the cable retainer means would simply provide a passageway which is straight and perpendicular to the longitudinal axis of the piston rod 26, and which is substantially adjacent to the bottom end of the cylinder 22. To provide such a passageway the fixed block portion 46 may be provided with a projection at its bottom end. This projection may have a top face which is perpendicular to the longitudinal axis of the piston rod 26 and which is spaced in a parallel fashion to the bottom end of the cylinder 22 for receiving the cable. In such an arrangement the block portion 48 would not have a projection, but would simply be a block which fits on top of the fixed block projection and extends thereabove to complete the passageway for the cable. Registering pins may be provided on the removable block for insertion in apertures within the projection of the fixed block and the two blocks may be held together by bolts.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

I claim:

1. An underwater cable cutter comprising:

a piston and cylinder, said cylinder being closed at a top end;

the piston having a rod which slidably extends through the bottom end of the cylinder;

the bottom end of the rod having a cutter edge which is capable of cutting a cable;

means mounted on the cylinder for retaining a cable for cutting by said cutting edge; and

an aperture in the cylinder for introducing sea pressure for actuating said piston.

2. An underwater cable cutter as claimed in claim 1 wherein:

the cable retainer means has a passageway which is capable of leading the cable at an angle to the longitudinal axis of the piston rod.

3. An underwater cable cutter as claimed in claim 1 wherein:

the cable retainer means has a passageway which curves said aperture is located in the removable top of the cylinder. 8. An underwater cable cutter as claimed in claim 7 including:

a plug which is insertable in said aperture for closing the cylinder from outside water pressure; and a line attached to the plug for pulling the plug from the aperture. 9. An underwater cable cutter as claimed in claim 8 formed by a cutting face on the rod which is substan-- 10 wherein:

tially coextensive with the longitudinal axis of the piston rod. 5. An underwater cable cutter as claimed in claim 4 wherein:

the block is divided into two portions, one block portion being rigidly fixed to the bottom end of the cylinder and the other block portion being removable from the fixed block portion; the fixed and removable block portions each have a respective projection which in combination from said passageway; and the projection of the fixed block portion has a planar face and the projection of the removable block portion has an arcuate face which is curved 90. 6. An underwater cable cutter as claimed in claim 5 wherein:

the fixed block portion has a pair of alignment holes;

and a pair of alignment pins are mounted on the projection of the removable block portion for registering with the alignment holes and positioning the block portions to form said passageway. 7. An underwater cable cutter as claimed in claim 1 wherein:

the cylinder has a removable top; and

said line is formed into a loop.

10. An underwater cable cutter as claimed in claim 1 wherein:

the cylinder has a removable top; and

a lift ring is mounted on said removable top.

11. An underwater cable cutter as claimed in claim 1 wherein:

the bottom end of the cylinder having a passageway which slidably receives the piston rod; and

FRANK T. YOST, Primary Examiner US. Cl. X.R. 

